s:Chapter 20 Carbohydrate Biosynthesis 1. Gluconeogenesis: The universal pathway for synthesis of glucose 2. Biosynthesis of glycogen, starch, and sucrose 3. CO2 fixation in plants(the Calvin Cycle) 4. Regulation of carbohydrate metabolism in plants
Chapter 20 Carbohydrate Biosynthesis 1. Gluconeogenesis: The universal pathway for synthesis of glucose. 2. Biosynthesis of glycogen, starch, and sucrose. 3. CO2 fixation in plants (the Calvin Cycle). 4. Regulation of carbohydrate metabolism in plants
1, Carbohydrates are synthesized from simple precursors via gluconeogenesis A few three-carbon compounds(including lactate, pyruvate, glycerol, and 3-phosphoglycerate) serve as the major precursors for carbohydrate (glucose) biosynthesis or gluconeogenesis The reactions of gluconeogenesis are essentially the same in different organisms The conversion of pyruvate to glucose is the central pathway in gluconeogenesis
1. Carbohydrates are synthesized from simple precursors via gluconeogenesis • A few three-carbon compounds (including lactate, pyruvate, glycerol, and 3-phosphoglycerate) serve as the major precursors for carbohydrate (glucose) biosynthesis, or gluconeogenesis. • The reactions of gluconeogenesis are essentially the same in different organisms. • The conversion of pyruvate to glucose is the central pathway in gluconeogenesis
Blood Other glucose Glycoproteins monosaccharides Sucrose Glycogen Disaccharides Glucose 6-phosphate Animals erg Plants Phosphoenolpyruvate Citric acid cycle Pyruvate Glucogenic Glycerol 3-Phosphoglycerate amino Lactate Triacylglycerols ce fixation
2, The opposing pathways of glycolysis and gluconeogenesis have 3 reactions different and 7 reactions in common The reversible reactions between pyruvate and glucose are shared by gluconeogenesis and glycolysis, but the irreversible reactions are different (bypassed? in gluconeogenesis
2. The opposing pathways of glycolysis and gluconeogenesis have 3 reactions different and 7 reactions in common • The reversible reactions between pyruvate and glucose are shared by gluconeogenesis and glycolysis, but the irreversible reactions are different (“bypassed” in gluconeogenesis)
Glyco y UDP Glucose 1-phosphate ATP Third 1, 3-Bisphosphoglycerat ADP ADP ADP Glucose 6-phosphate ATP Glycolysis 3-Phosphoglycerate pathway Glu Fructose 6-phosphate P fructose 2.6- 2-Phosphoglycerate Second AMP,“一→ fructose 2.6- bisphosphate Fructose 1, 6-bisphosphate Glyceraldehyde Dihydroxyacetone GDP 3-phosphate GTP ADP NAD. NADH NADH NADH 1. 3-Bisphosphoglycerate MalateNAD' Opposing pathways of NADt NADH glycolysis and gluconeogenesis Oxaloacetate ADP with 3 different and 7 common ATP Alanine >Pyruvate reactions Pyruvate Alanine
Opposing pathways of glycolysis and gluconeogenesis: with 3 different and 7 common reactions